package cn.dinkevin.xui.util;

import com.rt.base64.BASE64Decoder;
import com.rt.base64.BASE64Encoder;

import java.io.IOException;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

/**
 * DES 加解密工具辅助类
 * Created by chengpengfei on 2017/4/26.
 * Copyright ©2017 juziwl, All Rights Reserved.
 */

public final class DESUtil {

    private DESUtil(){}

    private final static String DES = "DES";
    private static final String CIPHER_ALGORITHM_CBC = "DES/CBC/PKCS5Padding";
//	private static final String CIPHER_ALGORITHM_ECB = "DES/ECB/PKCS5Padding";

    /**
     * Description 根据键值进行加密
     *
     * @param data
     * @param key
     *            加密键byte数组
     * @return
     * @throws Exception
     */
    public static String encrypt(String data, String key) throws Exception {
        byte[] bt = encrypt(data.getBytes(), key.getBytes());
        String strs = new BASE64Encoder().encode(bt);
        return strs;
    }

    /**
     * Description 根据键值进行解密
     *
     * @param data
     * @param key
     *            加密键byte数组
     * @return
     * @throws IOException
     * @throws Exception
     */
    public static String decrypt(String data, String key) throws IOException, Exception {
        if (data == null)
            return null;
        BASE64Decoder decoder = new BASE64Decoder();
        byte[] buf = decoder.decodeBuffer(data);
        byte[] bt = decrypt(buf, key.getBytes());
        return new String(bt);
    }

    /**
     * Description 根据键值进行加密
     *
     * @param data
     * @param key
     *            加密键byte数组
     * @return
     * @throws Exception
     */
    private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
        // 生成一个可信任的随机数源
//		SecureRandom sr = new SecureRandom();

        // 从原始密钥数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);

        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey secureKey = keyFactory.generateSecret(dks);

        // Cipher对象实际完成加密操作
        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM_CBC);

        IvParameterSpec iv = new IvParameterSpec("12345678".getBytes());
        AlgorithmParameterSpec paramSpec = iv;
        cipher.init(Cipher.ENCRYPT_MODE, secureKey, paramSpec);

        // 用密钥初始化Cipher对象
//		cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
        return cipher.doFinal(data);
    }

    /**
     * Description 根据键值进行解密
     *
     * @param data
     * @param key
     *            加密键byte数组
     * @return
     * @throws Exception
     */
    private static byte[] decrypt(byte[] data, byte[] key) throws Exception {

        // 生成一个可信任的随机数源
//		SecureRandom sr = new SecureRandom();

        // 从原始密钥数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);

        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey secureKey = keyFactory.generateSecret(dks);

        // Cipher对象实际完成解密操作
        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM_CBC);
        IvParameterSpec iv = new IvParameterSpec("12345678".getBytes());
        AlgorithmParameterSpec paramSpec = iv;
        cipher.init(Cipher.DECRYPT_MODE, secureKey, paramSpec);

        // 用密钥初始化Cipher对象
//		cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
        return cipher.doFinal(data);
    }
}
